The present invention relates to a removable disk drive provided with an antistatic component, and more particularly, to a removable disk drive provided with an electrostatic brush which does not produce noise and metal powder when a spindle motor shaft is rotated. It is to be noted that a removable disk as used herein includes disks such as a floppy disk (a flexible disk), a magneto-optical disk, a Digital Versatile Disk-Read Only Memory (DVD-ROM), a DVD-Random Access Memory (DVD-RAM), a DVD-Recordable (DVD-R), a DVD-Re-Writable (DVD-RW), a Compact Disk-Read Only Memory (CD-ROM), a CD-Recordable (CD-R), and a CD-Re-Writable (CD-R/W).
Conventionally, a countermeasure against static electricity is an important problem of a removable disk drive. Under an environment of low humidity, it is often the case that the human body is charged with static electricity. When the person holds a recording disk, the recording disk is charged with static electricity. If the charged recording disk is inserted in a removable disk drive without a countermeasure against static electricity, the static electricity is discharged to an electric circuit in the drive, which may cause malfunction of or damage to the electric circuit.
Referring to FIG. 3, in a recording disk 6, metal portions, i.e., a shutter 7 and a hub 8, are easily charged with static electricity. It is to be noted that the shutter 7 opens and closes a insertion slot for a recording/reproducing head (now shown). The shutter 7 is structured to be closed when the recording disk 6 is not inserted in the removable disk drive and to be open when the recording disk 6 is inserted in the removable disk drive to prevent foreign matters from entering the recording disk 6 while the recording disk 6 is not inserted therein. The hub 8 engages with a spindle motor shaft provided in the removable disk drive when the recording disk 6 is inserted in the removable disk drive to locate the recording disk 6 and to transmit the rotation of the spindle motor shaft to a recording medium (not shown) in the recording disk 6.
FIGS. 4 and 5 are sectional views illustrating the structure and operation of a conventional removable disk drive with a countermeasure against static electricity. FIG. 4 illustrates a state when operation of inserting the recording disk 6 in a removable disk drive 12 is on the way, while FIG. 5 illustrates a state when the insertion of the recording disk 6 in the removable disk drive 12 is completed. As illustrated in FIGS. 4 and 5, in the conventional removable disk drive 12, an electrostatic brush 11 which is always in contact with a housing 4 and a spindle motor shuttle 1 of the removable disk drive 12 is provided. Static electricity with which the recording disk 6 is charged is discharged through the spindle motor shaft 1 and the electrostatic brush 11 to the housing 4.
However, the conventional technology has the following problems. As illustrated in FIGS. 4 and 5, the electrostatic brush 11 is structured to be in contact with the spindle motor shaft 1 not only when the recording disk 6 is not inserted in the removable disk drive 12 and when insertion of the recording disk 6 in the removable disk drive 12 is on the way, but also when the recording disk 6 is completely inserted. Since the spindle motor shaft 1 rotates when data is read from and written to the recording disk 6, this rotation is accompanied by rubbing of the electrostatic brush 11 with the spindle motor shaft 1. Therefore, there is a problem that noise is produced when the spindle motor shaft 1 is rotated.
Further, when the electrostatic brush 11 is used for a long time, wear is caused due to the rotation of the spindle motor shaft 1 to produce metal powder of the electrostatic brush 11 and the spindle motor shaft 1. Therefore, there is a problem that the metal powder attaches to the recording disk 6 to damage the recording disk 6 to cause abrasions thereon, for example, and thus, cause a reading error.
Further, since the electrostatic brush 11 is a load on the rotation of the spindle motor shaft 1, electric power consumption accompanied by the rotation of the spindle motor shaft 1 is increased and the amount of generated heat is increased accordingly.
The present invention is made in view of the above problems, and an object of the present invention is to provide a removable disk drive which can discharge static electricity with which a recording disk is charged, which does not produce noise and metal powder when a spindle motor shaft is rotated, and the electric power consumption of which is small.
According to the present invention, a removable disk drive having a recording disk inserted therein for reading data from and writing data to the recording disk comprises a housing, a spindle motor shaft provided in the housing for rotating the recording disk, and an electrostatic brush provided between the housing and the spindle motor shaft, the electrostatic brush coming in contact with the housing and the spindle motor shaft and being formed of a conductive material for discharging static electricity of the recording disk to the housing, and is characterized in that the electrostatic brush is in contact with the spindle motor shaft and the housing when operation of inserting the recording disk is on the way and is out of contact with the spindle motor shaft when the spindle motor shaft is rotating after insertion of the recording disk is completed.
According to the present invention, since the electrostatic brush of the removable disk drive is out of contact with the spindle motor shaft when the spindle motor shaft is rotating, the rotation of the spindle motor shaft is not accompanied by rubbing of the electrostatic brush, and thus, noise and metal powder can be prevented from being produced.
Further, the electrostatic brush may be structured to be formed of a resilient material or to have a spring structure and to come in contact with the spindle motor shaft with predetermined pressing force.
This can ensure contact of the electrostatic brush with the spindle motor shaft.